This invention relates generally to a well assembly and more particularly to an improved apparatus for recovering liquid products, including contaminants, from below ground level.
This systems is especially beneficial for recovering hydrocarbon products which have either leaked, spilled or seeped into the ground resulting in comtaminated soil and ground water. Environmental agencies are particularly concerned with the clean-up of such spills such as in the area of petroleum refineries, tank farms and even an individual automobile service station wherein a storage tank may have ruptured or is leaking.
Since the hydrocarbons exhibit a specific gravity less than that of water, the usual remedy for the recovery of these contaminants comprises the drilling of a well and the lowering of two pumps therein. Water is extracted by one of the pumps following which the surface of the water table developes an inverted cone shape surrounding the well bore. The subsurface contaminant seeks the lower level created by the depressed area of the center of this cone while disposed atop the heavier water. The other pump is operated to remove the accumulated column of contaminant disposed atop the water column within the well.
Prior efforts to accomplish the foregoing have comprised various assemblies including downhole pumps and electrical probes such as employed in the "Petropurge" system as produced by Nepcco. A further prior example is found in the apparatus as produced by Ejector Systems, Inc and which comprises a downhole vessel having a valved inlet permitting filling of the vessel with the surrounding fluid following which the vessel is pressurized to eject the fluid through a discharge pipe. Another example of a recovery system for below ground contaminants will be found in the patent to Kimberlin U.S. Pat. No. 4,466,777 dated Aug. 21, 1984 and which discloses the use of downhole pumps and electical probes.
By the present invention, an improved system is presented wherein a greatly simplified arrangement is provided not usually requiring the use of any downhole pumps, sensors or electrical probes and which is relatively inexpensive to construct, maintain and operate. This system utilizes the difference in the specific gravity of water and the petroleum product to separate the two fluids in the recovery well and individually withdraws each constituent as it accumulates in the zone of the depressed cone.
Accordingly, one of the objects of the present invention is to provide an improved product recovery system for subterranean fluids including a pair of withdrawal pipes extending into a well with their respective intakes disposed at different levels and with one of these pipes surrounded by a tube having its intake located at still a further lower level to provide for the separation of hydrocarbons from water within the well casing.
Still another object of the present invention is to provide an improved product recovery system for a well including a pair of withdrawal pipes having intakes each located within the zone of a fluid contaminant within the well with one of these pipes further surrounded by a separator tube having its intake located below the zone of the contaminant and wherein separate pump means respectively extracts water and contaminant through the two pipes.
A further object of the present invention is to provide an improved product recovery system inclding a plurality of pipes having their intakes disposed at a level within a zone of fluid contaminant within a well with one of the pipes serving to extract water from the lower reaches of the well and including stripping means within that pipe to enhance the removal of dissolved volatile contaminants by contact with air entrained within water being extracted through the water pipe.